1 """Database management."""
2 from __future__ import annotations
4 from os.path import isfile
5 from difflib import Differ
6 from sqlite3 import connect as sql_connect, Cursor, Row
7 from typing import Any, Self, TypeVar, Generic, Callable
8 from plomtask.exceptions import HandledException, NotFoundException
9 from plomtask.dating import valid_date
11 EXPECTED_DB_VERSION = 5
12 MIGRATIONS_DIR = 'migrations'
13 FILENAME_DB_SCHEMA = f'init_{EXPECTED_DB_VERSION}.sql'
14 PATH_DB_SCHEMA = f'{MIGRATIONS_DIR}/{FILENAME_DB_SCHEMA}'
17 class UnmigratedDbException(HandledException):
18 """To identify case of unmigrated DB file."""
22 """Represents the sqlite3 database's file."""
23 # pylint: disable=too-few-public-methods
25 def __init__(self, path: str) -> None:
30 def create_at(cls, path: str) -> DatabaseFile:
31 """Make new DB file at path."""
32 with sql_connect(path) as conn:
33 with open(PATH_DB_SCHEMA, 'r', encoding='utf-8') as f:
34 conn.executescript(f.read())
35 conn.execute(f'PRAGMA user_version = {EXPECTED_DB_VERSION}')
39 def migrate(cls, path: str) -> DatabaseFile:
40 """Apply migrations from_version to EXPECTED_DB_VERSION."""
41 migrations = cls._available_migrations()
42 from_version = cls._get_version_of_db(path)
43 migrations_todo = migrations[from_version+1:]
44 for j, filename in enumerate(migrations_todo):
45 with sql_connect(path) as conn:
46 with open(f'{MIGRATIONS_DIR}/{filename}', 'r',
47 encoding='utf-8') as f:
48 conn.executescript(f.read())
49 user_version = from_version + j + 1
50 with sql_connect(path) as conn:
51 conn.execute(f'PRAGMA user_version = {user_version}')
54 def _check(self) -> None:
55 """Check file exists, and is of proper DB version and schema."""
56 if not isfile(self.path):
57 raise NotFoundException
58 if self._user_version != EXPECTED_DB_VERSION:
59 raise UnmigratedDbException()
60 self._validate_schema()
63 def _available_migrations() -> list[str]:
64 """Validate migrations directory and return sorted entries."""
65 msg_too_big = 'Migration directory points beyond expected DB version.'
66 msg_bad_entry = 'Migration directory contains unexpected entry: '
67 msg_missing = 'Migration directory misses migration of number: '
69 for entry in listdir(MIGRATIONS_DIR):
70 if entry == FILENAME_DB_SCHEMA:
72 toks = entry.split('_', 1)
74 raise HandledException(msg_bad_entry + entry)
77 except ValueError as e:
78 raise HandledException(msg_bad_entry + entry) from e
79 if i > EXPECTED_DB_VERSION:
80 raise HandledException(msg_too_big)
81 migrations[i] = toks[1]
83 for i in range(EXPECTED_DB_VERSION + 1):
84 if i not in migrations:
85 raise HandledException(msg_missing + str(i))
86 migrations_list += [f'{i}_{migrations[i]}']
87 return migrations_list
90 def _get_version_of_db(path: str) -> int:
91 """Get DB user_version, fail if outside expected range."""
92 sql_for_db_version = 'PRAGMA user_version'
93 with sql_connect(path) as conn:
94 db_version = list(conn.execute(sql_for_db_version))[0][0]
95 if db_version > EXPECTED_DB_VERSION:
96 msg = f'Wrong DB version, expected '\
97 f'{EXPECTED_DB_VERSION}, got unknown {db_version}.'
98 raise HandledException(msg)
99 assert isinstance(db_version, int)
103 def _user_version(self) -> int:
104 """Get DB user_version."""
105 return self._get_version_of_db(self.path)
107 def _validate_schema(self) -> None:
108 """Compare found schema with what's stored at PATH_DB_SCHEMA."""
110 def reformat_rows(rows: list[str]) -> list[str]:
114 for subrow in row.split('\n'):
115 subrow = subrow.rstrip()
118 for i, c in enumerate(subrow):
123 elif ',' == c and 0 == in_parentheses:
127 segment = subrow[prev_split:i].strip()
129 new_row += [f' {segment}']
131 segment = subrow[prev_split:].strip()
133 new_row += [f' {segment}']
134 new_row[0] = new_row[0].lstrip()
135 new_row[-1] = new_row[-1].lstrip()
136 if new_row[-1] != ')' and new_row[-3][-1] != ',':
137 new_row[-3] = new_row[-3] + ','
138 new_row[-2:] = [' ' + new_row[-1][:-1]] + [')']
139 new_rows += ['\n'.join(new_row)]
142 sql_for_schema = 'SELECT sql FROM sqlite_master ORDER BY sql'
143 msg_err = 'Database has wrong tables schema. Diff:\n'
144 with sql_connect(self.path) as conn:
145 schema_rows = [r[0] for r in conn.execute(sql_for_schema) if r[0]]
146 schema_rows = reformat_rows(schema_rows)
147 retrieved_schema = ';\n'.join(schema_rows) + ';'
148 with open(PATH_DB_SCHEMA, 'r', encoding='utf-8') as f:
149 stored_schema = f.read().rstrip()
150 if stored_schema != retrieved_schema:
151 diff_msg = Differ().compare(retrieved_schema.splitlines(),
152 stored_schema.splitlines())
153 raise HandledException(msg_err + '\n'.join(diff_msg))
156 class DatabaseConnection:
157 """A single connection to the database."""
159 def __init__(self, db_file: DatabaseFile) -> None:
160 self.conn = sql_connect(db_file.path)
162 def commit(self) -> None:
163 """Commit SQL transaction."""
166 def exec(self, code: str, inputs: tuple[Any, ...] = tuple()) -> Cursor:
167 """Add commands to SQL transaction."""
168 return self.conn.execute(code, inputs)
170 def exec_on_vals(self, code: str, inputs: tuple[Any, ...]) -> Cursor:
171 """Wrapper around .exec appending adequate " (?, …)" to code."""
172 q_marks_from_values = '(' + ','.join(['?'] * len(inputs)) + ')'
173 return self.exec(f'{code} {q_marks_from_values}', inputs)
175 def close(self) -> None:
176 """Close DB connection."""
179 def rewrite_relations(self, table_name: str, key: str, target: int | str,
180 rows: list[list[Any]], key_index: int = 0) -> None:
181 # pylint: disable=too-many-arguments
182 """Rewrite relations in table_name to target, with rows values.
184 Note that single rows are expected without the column and value
185 identified by key and target, which are inserted inside the function
188 self.delete_where(table_name, key, target)
190 values = tuple(row[:key_index] + [target] + row[key_index:])
191 self.exec_on_vals(f'INSERT INTO {table_name} VALUES', values)
193 def row_where(self, table_name: str, key: str,
194 target: int | str) -> list[Row]:
195 """Return list of Rows at table where key == target."""
196 return list(self.exec(f'SELECT * FROM {table_name} WHERE {key} = ?',
199 # def column_where_pattern(self,
203 # keys: list[str]) -> list[Any]:
204 # """Return column of rows where one of keys matches pattern."""
205 # targets = tuple([f'%{pattern}%'] * len(keys))
206 # haystack = ' OR '.join([f'{k} LIKE ?' for k in keys])
207 # sql = f'SELECT {column} FROM {table_name} WHERE {haystack}'
208 # return [row[0] for row in self.exec(sql, targets)]
210 def column_where(self, table_name: str, column: str, key: str,
211 target: int | str) -> list[Any]:
212 """Return column of table where key == target."""
213 return [row[0] for row in
214 self.exec(f'SELECT {column} FROM {table_name} '
215 f'WHERE {key} = ?', (target,))]
217 def column_all(self, table_name: str, column: str) -> list[Any]:
218 """Return complete column of table."""
219 return [row[0] for row in
220 self.exec(f'SELECT {column} FROM {table_name}')]
222 def delete_where(self, table_name: str, key: str,
223 target: int | str) -> None:
224 """Delete from table where key == target."""
225 self.exec(f'DELETE FROM {table_name} WHERE {key} = ?', (target,))
228 BaseModelId = TypeVar('BaseModelId', int, str)
229 BaseModelInstance = TypeVar('BaseModelInstance', bound='BaseModel[Any]')
232 class BaseModel(Generic[BaseModelId]):
233 """Template for most of the models we use/derive from the DB."""
235 to_save_simples: list[str] = []
236 to_save_relations: list[tuple[str, str, str, int]] = []
237 versioned_defaults: dict[str, str | float] = {}
238 add_to_dict: list[str] = []
239 id_: None | BaseModelId
240 cache_: dict[BaseModelId, Self]
241 to_search: list[str] = []
242 can_create_by_id = False
244 sorters: dict[str, Callable[..., Any]] = {}
246 def __init__(self, id_: BaseModelId | None) -> None:
247 if isinstance(id_, int) and id_ < 1:
248 msg = f'illegal {self.__class__.__name__} ID, must be >=1: {id_}'
249 raise HandledException(msg)
250 if isinstance(id_, str) and "" == id_:
251 msg = f'illegal {self.__class__.__name__} ID, must be non-empty'
252 raise HandledException(msg)
255 def __hash__(self) -> int:
256 hashable = [self.id_] + [getattr(self, name)
257 for name in self.to_save_simples]
258 for definition in self.to_save_relations:
259 attr = getattr(self, definition[2])
260 hashable += [tuple(rel.id_ for rel in attr)]
261 for name in self.to_save_versioned():
262 hashable += [hash(getattr(self, name))]
263 return hash(tuple(hashable))
265 def __eq__(self, other: object) -> bool:
266 if not isinstance(other, self.__class__):
268 return hash(self) == hash(other)
270 def __lt__(self, other: Any) -> bool:
271 if not isinstance(other, self.__class__):
272 msg = 'cannot compare to object of different class'
273 raise HandledException(msg)
274 assert isinstance(self.id_, int)
275 assert isinstance(other.id_, int)
276 return self.id_ < other.id_
279 def to_save_versioned(cls) -> list[str]:
280 """Return keys of cls.versioned_defaults assuming we wanna save 'em."""
281 return list(cls.versioned_defaults.keys())
284 def as_dict(self) -> dict[str, object]:
285 """Return self as (json.dumps-compatible) dict."""
286 library: dict[str, dict[str, object] | dict[int, object]] = {}
287 d: dict[str, object] = {'id': self.id_, '_library': library}
288 for to_save in self.to_save_simples:
289 attr = getattr(self, to_save)
290 if hasattr(attr, 'as_dict_into_reference'):
291 d[to_save] = attr.as_dict_into_reference(library)
294 if len(self.to_save_versioned()) > 0:
296 for k in self.to_save_versioned():
297 attr = getattr(self, k)
298 assert isinstance(d['_versioned'], dict)
299 d['_versioned'][k] = attr.history
300 for r in self.to_save_relations:
302 l: list[int | str] = []
303 for rel in getattr(self, attr_name):
304 l += [rel.as_dict_into_reference(library)]
306 for k in self.add_to_dict:
307 d[k] = [x.as_dict_into_reference(library)
308 for x in getattr(self, k)]
311 def as_dict_into_reference(self,
312 library: dict[str, dict[str | int, object]]
314 """Return self.id_ while writing .as_dict into library."""
315 # NB: For tighter mypy testing, we might prefer the library argument
316 # to be of type dict[str, dict[str, object] | dict[int, object]
317 # instead. But my current coding knowledge only manage to make that
318 # work by turning the code much more complex, so let's leave it at
321 def into_library(library: dict[str, dict[str | int, object]],
326 if cls_name not in library:
327 library[cls_name] = {}
328 if id_ in library[cls_name]:
329 if library[cls_name][id_] != d:
330 msg = 'Unexpected inequality of entries for ' +\
331 f'_library at: {cls_name}/{id_}'
332 raise HandledException(msg)
334 library[cls_name][id_] = d
336 as_dict = self.as_dict
337 assert isinstance(as_dict['_library'], dict)
338 for cls_name, dict_of_objs in as_dict['_library'].items():
339 for id_, obj in dict_of_objs.items():
340 into_library(library, cls_name, id_, obj)
341 del as_dict['_library']
342 assert self.id_ is not None
343 into_library(library, self.__class__.__name__, self.id_, as_dict)
344 assert isinstance(as_dict['id'], (int, str))
348 def name_lowercase(cls) -> str:
349 """Convenience method to return cls' name in lowercase."""
350 return cls.__name__.lower()
353 def sort_by(cls, seq: list[Any], sort_key: str, default: str = 'title'
355 """Sort cls list by cls.sorters[sort_key] (reverse if '-'-prefixed).
357 Before cls.sorters[sort_key] is applied, seq is sorted by .id_, to
358 ensure predictability where parts of seq are of same sort value.
361 if len(sort_key) > 1 and '-' == sort_key[0]:
362 sort_key = sort_key[1:]
364 if sort_key not in cls.sorters:
366 seq.sort(key=lambda x: x.id_, reverse=reverse)
367 sorter: Callable[..., Any] = cls.sorters[sort_key]
368 seq.sort(key=sorter, reverse=reverse)
370 sort_key = f'-{sort_key}'
374 # (we primarily use the cache to ensure we work on the same object in
375 # memory no matter where and how we retrieve it, e.g. we don't want
376 # .by_id() calls to create a new object each time, but rather a pointer
377 # to the one already instantiated)
379 def __getattribute__(self, name: str) -> Any:
380 """Ensure fail if ._disappear() was called, except to check ._exists"""
381 if name != '_exists' and not super().__getattribute__('_exists'):
382 raise HandledException('Object does not exist.')
383 return super().__getattribute__(name)
385 def _disappear(self) -> None:
386 """Invalidate object, make future use raise exceptions."""
387 assert self.id_ is not None
388 if self._get_cached(self.id_):
390 to_kill = list(self.__dict__.keys())
396 def empty_cache(cls) -> None:
397 """Empty class's cache, and disappear all former inhabitants."""
398 # pylint: disable=protected-access
399 # (cause we remain within the class)
400 if hasattr(cls, 'cache_'):
401 to_disappear = list(cls.cache_.values())
402 for item in to_disappear:
407 def get_cache(cls: type[BaseModelInstance]) -> dict[Any, BaseModel[Any]]:
408 """Get cache dictionary, create it if not yet existing."""
409 if not hasattr(cls, 'cache_'):
410 d: dict[Any, BaseModel[Any]] = {}
415 def _get_cached(cls: type[BaseModelInstance],
416 id_: BaseModelId) -> BaseModelInstance | None:
417 """Get object of id_ from class's cache, or None if not found."""
418 cache = cls.get_cache()
421 assert isinstance(obj, cls)
425 def cache(self) -> None:
426 """Update object in class's cache.
428 Also calls ._disappear if cache holds older reference to object of same
429 ID, but different memory address, to avoid doing anything with
433 raise HandledException('Cannot cache object without ID.')
434 cache = self.get_cache()
435 old_cached = self._get_cached(self.id_)
436 if old_cached and id(old_cached) != id(self):
437 # pylint: disable=protected-access
438 # (cause we remain within the class)
439 old_cached._disappear()
440 cache[self.id_] = self
442 def _uncache(self) -> None:
443 """Remove self from cache."""
445 raise HandledException('Cannot un-cache object without ID.')
446 cache = self.get_cache()
449 # object retrieval and generation
452 def from_table_row(cls: type[BaseModelInstance],
453 # pylint: disable=unused-argument
454 db_conn: DatabaseConnection,
455 row: Row | list[Any]) -> BaseModelInstance:
456 """Make from DB row (sans relations), update DB cache with it."""
458 assert obj.id_ is not None
459 for attr_name in cls.to_save_versioned():
460 attr = getattr(obj, attr_name)
461 table_name = attr.table_name
462 for row_ in db_conn.row_where(table_name, 'parent', obj.id_):
463 attr.history_from_row(row_)
468 def by_id(cls, db_conn: DatabaseConnection, id_: BaseModelId) -> Self:
469 """Retrieve by id_, on failure throw NotFoundException.
471 First try to get from cls.cache_, only then check DB; if found,
476 obj = cls._get_cached(id_)
478 for row in db_conn.row_where(cls.table_name, 'id', id_):
479 obj = cls.from_table_row(db_conn, row)
483 raise NotFoundException(f'found no object of ID {id_}')
486 def by_id_or_create(cls, db_conn: DatabaseConnection,
487 id_: BaseModelId | None
489 """Wrapper around .by_id, creating (not caching/saving) if not find."""
490 if not cls.can_create_by_id:
491 raise HandledException('Class cannot .by_id_or_create.')
495 return cls.by_id(db_conn, id_)
496 except NotFoundException:
500 def all(cls: type[BaseModelInstance],
501 db_conn: DatabaseConnection) -> list[BaseModelInstance]:
502 """Collect all objects of class into list.
504 Note that this primarily returns the contents of the cache, and only
505 _expands_ that by additional findings in the DB. This assumes the
506 cache is always instantly cleaned of any items that would be removed
509 items: dict[BaseModelId, BaseModelInstance] = {}
510 for k, v in cls.get_cache().items():
511 assert isinstance(v, cls)
513 already_recorded = items.keys()
514 for id_ in db_conn.column_all(cls.table_name, 'id'):
515 if id_ not in already_recorded:
516 item = cls.by_id(db_conn, id_)
517 assert item.id_ is not None
518 items[item.id_] = item
519 return list(items.values())
522 def by_date_range_with_limits(cls: type[BaseModelInstance],
523 db_conn: DatabaseConnection,
524 date_range: tuple[str, str],
525 date_col: str = 'day'
526 ) -> tuple[list[BaseModelInstance], str,
528 """Return list of items in DB within (closed) date_range interval.
530 If no range values provided, defaults them to 'yesterday' and
531 'tomorrow'. Knows to properly interpret these and 'today' as value.
533 start_str = date_range[0] if date_range[0] else 'yesterday'
534 end_str = date_range[1] if date_range[1] else 'tomorrow'
535 start_date = valid_date(start_str)
536 end_date = valid_date(end_str)
538 sql = f'SELECT id FROM {cls.table_name} '
539 sql += f'WHERE {date_col} >= ? AND {date_col} <= ?'
540 for row in db_conn.exec(sql, (start_date, end_date)):
541 items += [cls.by_id(db_conn, row[0])]
542 return items, start_date, end_date
545 def matching(cls: type[BaseModelInstance], db_conn: DatabaseConnection,
546 pattern: str) -> list[BaseModelInstance]:
547 """Return all objects whose .to_search match pattern."""
548 items = cls.all(db_conn)
552 for attr_name in cls.to_search:
553 toks = attr_name.split('.')
556 attr = getattr(parent, tok)
566 def save(self, db_conn: DatabaseConnection) -> None:
567 """Write self to DB and cache and ensure .id_.
569 Write both to DB, and to cache. To DB, write .id_ and attributes
570 listed in cls.to_save_[simples|versioned|_relations].
572 Ensure self.id_ by setting it to what the DB command returns as the
573 last saved row's ID (cursor.lastrowid), EXCEPT if self.id_ already
574 exists as a 'str', which implies we do our own ID creation (so far
575 only the case with the Day class, where it's to be a date string.
577 values = tuple([self.id_] + [getattr(self, key)
578 for key in self.to_save_simples])
579 table_name = self.table_name
580 cursor = db_conn.exec_on_vals(f'REPLACE INTO {table_name} VALUES',
582 if not isinstance(self.id_, str):
583 self.id_ = cursor.lastrowid # type: ignore[assignment]
585 for attr_name in self.to_save_versioned():
586 getattr(self, attr_name).save(db_conn)
587 for table, column, attr_name, key_index in self.to_save_relations:
588 assert isinstance(self.id_, (int, str))
589 db_conn.rewrite_relations(table, column, self.id_,
591 in getattr(self, attr_name)], key_index)
593 def remove(self, db_conn: DatabaseConnection) -> None:
594 """Remove from DB and cache, including dependencies."""
595 if self.id_ is None or self._get_cached(self.id_) is None:
596 raise HandledException('cannot remove unsaved item')
597 for attr_name in self.to_save_versioned():
598 getattr(self, attr_name).remove(db_conn)
599 for table, column, attr_name, _ in self.to_save_relations:
600 db_conn.delete_where(table, column, self.id_)
602 db_conn.delete_where(self.table_name, 'id', self.id_)